The present invention relates to synthetic polypeptides that are made by the reaction of amino acids to give specific compounds that have outstanding properties when applied to hair. The compounds of the present invention are rich relatively low molecular weight polypeptides, having a molecular weight up to 2000 Daltons. These polypeptides are rich in sulfur bearing amino acids, most specifically cysteine and are also rich in proline. This low molecular weight and the enhanced content of specific amino acids results in (a) essentially linear proteins; (b) penetration of the hair shaft due to lower molecular weight and (c) reaction with treated hair to reform di-sulfide bonds between the natural sulfur bearing amino acids in the hair protein and the polypeptide.
Human hair is treated in a number of ways that affect its structure. The relaxing of hair, bleaching of hair, and permanent waving of the hair are three examples of how chemicals are applied to the hair in an attempt to alter its structure. The processes all open up the disulfide bond that is present in hair. It is this disulfide bond that regulates the curl in the hair and many other properties. Since the treatment of hair is very harsh to the hair, it is highly desirable to apply materials to treat the hair to minimize ongoing damage and to preserve the intended effect. Proteins per se are not generally effective in conditioning hair, since they are too large in molecular weight to penetrate the hair. Polypeptides can be effective if they are low enough molecular weight to penetrate. Many companies call these polypeptides made by hydrolysis xe2x80x9cproteinsxe2x80x9d.
Heretofore, these xe2x80x9cproteinsxe2x80x9d applied to the hair for conditioning and antistatic effect have been made by hydrolysis of natural proteins. The hydrolysis procedure makes use of either acidic alkaline or enzymatic processes. These processes actually destroy peptide bonds giving a mixture of different molecular weight polypeptides, and amino acids. This approach results in materials that have low efficiency on the hair.
The reason for this low efficiency is the fact that in hydrolysis the entire protein is reacted giving many polypeptides that have little or no functionality on hair. This lack of functionality may be due to (a) the fact that the polypeptide segments are globular, rather than linear, (b) the polypeptide contains little or no sulfur rich amino acids and (c) the polypeptide fails to penetrate the hair because they are too high molecular weight to penetrate the hair. We have surprisingly found that by synthesizing the amino acid sequence of interest, rather than degrading natural proteins, a highly functional product can be achieved. The polypeptide we synthesize is referred to as engineered polypeptides and can either be made in the laboratory using a protein synthesizer or can be made using genetically modified microbes like bacteria. Interestingly, these proteins will therefore not be based upon animal protein, making them of interest to today""s personal care market, where animal rights are a grave concern to many
Typical of the hydrolyzed protein U.S. Pat. No. 5,314,873 issued on May 24, 1994 to Tomita et al. It discloses the treatment of milk protein by hydrolysis to make hair and skin treating agents. This patent and others like it make use of native proteins that are degraded into polypeptides. The elevate levels of sulfur rich amino acids and proline are absent from these compounds.
Therefore, it is an object of the present invention to provide specific polypeptides having a molecular weight of up to 2,000 Daltons that are rich in sulfur bearing amino acids like cysteine and are likewise rich in the amino acid proline.
It is also an objective of the present invention to provide a process for treating hair that comprises contacting the hair with an effective conditioning amount of a specific polypeptide having a molecular-weight of up to 2,000 Daltons that are rich in sulfur bearing amino acids like cysteine and are likewise rich in the amino acid proline.
The present invention is related to a sequence of amino acids having between 20 and 60 amino acids in a polypeptide. In the sequence having 20 amino acid units, at least 2 cysteine units and at least 1 proline unit are present. In a sequence having 60 amino acids in the polypeptide, at least 6 cysteine units and at least 3 proline units are present.
The present invention allows for the custom synthesis of polypeptides that have specific functionality in conditioning hair. The presences of specific groups in the polypeptide at specific concentrations. Specifically, cysteine a sulfur rich amino acid must be present at a concentration that allows for it to react with native cysteine in the hair to keep the shape of the hair as treated. Cysteine is found in low concentrations in normal hair and the formation of the disulfide bond is generally attributed to the curl in hair. Additionally, proline, referred to as the coil breaker amino acid must be present at a suitable concentration in the molecule. This causes the polypeptide to be essentially linear rather than globular and allows for the cysteine""s sulfur group to bind with the hair""s sulfur groups.
Finally, the molecular weight needs to be low enough to penetrate the hair. Therefore, the polypeptide of the present invention will have between 20 and 60 amino acids in its sequence. It will have between 10% and 33% of those units being cysteine and between 5% and 15% proline. The remaining amino acid units in the polypeptide will be made up of some or all other amino acids.
The present invention provides for a process for conditioning hair and skin which comprises contacting the hair or skin with an effective conditioning concentration of a polypeptide having between 20 and 60 amino acids in a polypeptide, having cysteine as at least 10% of the amino acids units and proline as at least 5% of the amino acid units. The effective conditioning concentration ranges from between 0.1% and 25% by weight.
In a preferred embodiment the polypeptide has 20 amino acid units linked together, in which at least 2 units are cysteine and 1 is proline.
In a preferred embodiment the polypeptide has 20 amino acid units linked together, in which at least 2 units are cysteine and 1 is proline, with the proline unit being in the center of the molecule.
In a preferred embodiment the polypeptide has 40 amino acid units linked together, in which at least 2 units are cysteine, distributed throughout the molecule, and 1 is proline, with the proline unit being in the center of the molecule.
In a preferred embodiment the polypeptide has 60 amino acid units linked together, in which at least 6 units are cysteine and 3 is proline.
In a preferred embodiment the polypeptide has 40 amino acid units linked together, in which at least 6 units are cysteine and 3 is proline, with the proline units being distributed throughout the molecule.
In a preferred embodiment the polypeptide has 40 amino acid units linked together, in which at least 4 units are cysteine and 2 is proline.
In a preferred embodiment the polypeptide has 20 amino acid units linked together, in which at least 4 units are cysteine and 2 is proline, with the proline units being distributed throughout the molecule.